In the technology of X-ray dual energy, it is known to calculate specific images from the original energy images. In general, two X-ray images acquired at different X-ray energies are merged into one image. For example, the lung and the bones of the chest may be differentiated from each other with chest dual energy imaging.
For a dual energy soft tissue image, the two images acquired at different energies are subtracted using a scaling factor for the low energy image. What is visible in this soft tissue image is the structure of the lung vessels before the air background in the lungs because here the path through the tissue penetrates less tissue. The ribs are not visible in this image, so the added value of this image is that soft tissue structures like cancer nodules will bot be obscured by superimposed ribs, allowing a better detection.
For a dual energy bones image, the two images are subtracted from each other. The weight factor applied to the LOW image is different to the one used for the soft tissue image. When choosing the weight coefficients for the subtraction carefully, nearly only bones are visible and all soft tissue may be depicted with the same dark grey as the direct radiation next to the patient.
In spectral mammography, a mammography device is employed that comprises an X-ray detector that is adapted for differentiating X-rays of different energies. For example, WO 2013/076662 A1 discusses a type of spectral image processing.